Print ISSN: 1681-6900

Online ISSN: 2412-0758

Keywords : SWAT model

Hydrological Model for Derbendi-Khan Dam Reservoir Watershed Using SWAT Model

Thair S. Khayyun; Imzahim Abdulkareem; Ali M. Hayder

Engineering and Technology Journal, 2020, Volume 38, Issue 6, Pages 896-909
DOI: 10.30684/etj.v38i6A.890

In this study, the watershed’s runoff of Derbendi-Khan dam reservoir within the upper part of Diyala River reach the northeast of Iraq was modeled by Soil Water Assessment Tool (SWAT). The model calibration and validation were based on monthly measured inflow to the dam reservoir. They extended for a period between 1979 and 2008 with a warm-up period of two years, twenty-year for calibration, and eight-year for validation. Sequential Uncertainty Fitting version 2 (SUFI2) automatic calibration algorithm method used for model calibration and sensitivity analysis. Results demonstrate that the model performance for the studied watershed which is evaluated, with many statistical criteria, was very good. The sensitivity analysis pointed parameters (CH_K2, CN2 ALPHA_BF, SFTMP, SOL_AWC, and CH_N2) are the most useful parameters on runoff calibration for the studied watershed. Moreover, it was found that the average annual areal snowmelt ratio to the average annual areal precipitation during the simulation period is approximately 24%.

Impact of Climate Change on the Spatiotemporal Distribution of Stream Flow and Sediment Yield of Darbandikhan Watershed, Iraq

Mahmoud S. Al- Khafaji; Rana D. Al- Chalabi

Engineering and Technology Journal, 2020, Volume 38, Issue 2, Pages 265-276
DOI: 10.30684/etj.v38i2A.156

The impact of climate change on stream flow and sediment yield in Darbandikhan Watershed is an important challenge facing the water resources in Diyala River, Iraq. This impact was investigated using five Global Circulation Models (GCM) based climate change projection models from the A1B scenario of medium emission. The Soil and Water Assessment Tool (SWAT) was used to compute the temporal and spatial distribution of streamflow and sediment yield of the study area for the period 1984 to 2050. The daily-observed flow recorded in Darbandikhan Dam for the period from 1984 to 2013 was used as a base period for future projection. The initial results of SWAT were calibrated and validated using SUFI-2 of the SWAT-CUP program in daily time step considering the values of the Nash-Sutcliffe Efficiency (NSE) coefficient of determination (R2) as a Dual objective function. Results of NSE and R2 during the calibration (validation) periods were equal to 0.61 and 0.62(0.53 and 0.68), respectively. In addition, the average future prediction for the five climate models indicated that the average yearly flow and sediment yield in the watershed would decrease by about 49% and 44%, respectively, until the year 2050 compared with these of the base period from 1984 to 2013. Moreover, spatial analysis shows that 89.6 % and 90 % of stream flow and sediment come from the Iranian part of Darbandikhan watershed while the remaining small percent comes from Iraq, respectively. However, the middle and southern parts of Darbandikhan Watershed contribute by most of the stream flow of the watershed while the parts of lack land cover and steep slopes produce most the sediment.